The last few weeks I hatched fry from several species. In some cases, there are lots. Due to space limitations, I decided to put a few groups outdoors. Before that, they were fed twice with Artemia. Then they were put in 70 liter tanks with a stock of invertebrates that I fished and sieved from a ditch. Things seems to go great! There are some casualties of course, as the photo shows, but overall everything goes well and the fry even seem to grow faster than ever. The fry are from Austrolebias prognathus “Salamanca”, and charrua “Ruta1316”. If all goes well, I might do this more systematically.
We’re definitely beyond the days of the Ice Saints. The first sugar peas can be harvested and killifish can be moved outdoors. I’m preparing tanks for Austrolebias cheradophilus (La Paloma) and elongatus (Gral Conesa), the first two large species for which I have newly matured pairs this year. The tanks (70 liter) contain some tap water and mostly water from the alongside canal, plants, a good shot of mosquito larvae, tubifex and some peat. I will add netting to keep birds and mice out, and part of the tank will be shaded with a reed mat or a panel. The tanks are in the sun during morning hours.
I’m in Paris and the weather is great. For Austrolebias, it is important to avoid that the tanks heat up too much. In the past, I experimented with netting, different depths and different tank colours, all with some effects, and it is time to start planning ahead for this year.
Two ideas are under consideration. The first is putting tanks in a mesh tunnel, which provides ventilation and shade. The second idea in the pipeline is to copy a phenomenon which occurs in the field. There the water is often murky due to suspended clay particles. This provides a great experience: when it’s very hot and you step into a pond, at moderate depths your feet will be standing in fresh and cool water! The fish are there as well. So I’m going to buy a block of clay in a craft store and will turn some tanks murky this summer.
How to avoid tanks from freezing over in case they have to be left in the garden? The Build it Solar website lists many examples of solar heaters and other DIY projects. Particularly inspiring examples are the Solar Horse Tanks.
On the other hand, inside a wooden barn which is a bit better isolated than most greenhouses, it is maybe sufficient to have a large water mass for heat storage, for example by stacking a number of plastic tanks with water in a spot which receives much sunlight during the day, not too far from the tanks with fish.
Should be ready by next winter…
Today I decided to check how the fish in the greenhouse were faring. All tanks were frozen over with at least five centimeters of ice. From one tank containing two male Austrolebias apaii and one male Austrolebias vazferreirai, I removed the ice cover. All three fish were still alive, but my intervention did seem to distress the apaii, which I euthanized immediately. I did not check the other tanks.
More later. According weather forecasts, the frost period should end soon.
Europe is suffering under a cold spell. Austrolebias don’t necessarily die when it freezes. I’ve filled a small greenhouse with 90 liter tanks, some containing few old fish bred in 2010 and early in 2011. These fish are too old and too large to transport to a different site and have already survived a cold spell outdoors, with 3 cm of ice on their tanks. They are otherwise healthy. I want to give them a chance to reproduce in spring and therefore decided not to disturb them nor euthanize them.
In the greenhouse, during the night, tanks have so far frozen over with ice of about 1 cm thick. Since cold weather usually means sunshine, the greenhouse heats up during the day, removing the ice cover again and allowing the fish to breathe well. The total amount of water in the greenhouse is large, about 400 liter. I hope everything goes well, but there is a risk of failure. Then I will need to invent a better system in order to protect my old fish; or move or euthanize them all before winter.
Many Austrolebias species, especially those occurring near the Atlantic coast, experience cold conditions during winter. It is therefore no problem at all to keep them for a prolonged time at relatively low temperatures. Even between five and ten degrees C. That can be done in an unheated or mildly heated greenhouse. Mind not to disturb the fish too much, and that they will eat little and lay few eggs. One can basically feed once a week when they are kept in tanks of 40 liter or more.